Exposed water main in basement and dehumidifier options

I have a cut out in the basement slab where the water main comes into the house.

This is the spot where water came up and in and flooded more than half of the basement a few years back. I then put in the sump pump on an emergency basis.

Now that I have some time on my hands, I plan on addressing this as well as the humidity in the basement.

Questions:

1) Should I do anything about the cut out for the water main? Do most people have this set up? i.e. cover it up? Fill with gravel? Cement? I would think not wise to seal it permanently in case something ever happens to the piping.

2) Sump pump - I used a home depot orange bucket with a bunch of holes drilled in it wrapped with a porous cloth as a stop gap. Should I consider digging way deeper with a much larger sump pit bucket? The sump works now...but I suspect it's probably not deep enough as I see plenty of water in both cut outs.

3) Considering a larger therma stor dehumidifier. Basement is 38.5' x 25' and will not be finished. I will be putting down FLOR carpet tiles after I figure out how to address some dampness coming out of the floor and the walls in a few spots (very minor but evident). Anybody used the stand alone units? I was thinking I would get he cheapest one as their 1800-2500 sq ft capactiy would seem more than enough. I currently have a soleusair unit I got from home depot that does 30 pints/day that seems to run all the time when set to 65% RH. Basement can get humid although I never get condensation.

4) If I manually actuate the sump say 20-30 times I can get the water in the cutout for the water main to go down. Sometimes it's bone dry there.....But I'm also getting water all the way on the other side of the floor that is on the high side of the hill.

Doesn't appear so. When I dug the pit for the sump, there was nothing below the concrete floor. I have a 3' ditch on the high side spanning past the house that's filled with gravel + 4" perforated pip to catch the water before it rolls down the hill. That connects up with all the gutters and all the water is at least pushed away from the house...But no french drain.

First, you can fill in the space around the sump can with pea-gravel, and patch the slab with concrete at that location. You may want to cut in a fiber-cement board cover for the pit where the water main comes in, but leave it otherwise open.

Digging the sump deeper won't really address the water table or drainage issue much. As long as the water level is below the slab, being 2" below isn't much different from being 12" below. To get serious about it would require digging down to the footings along the entire perimeter and installing drain-tile pea gravel to direct the water incursions at the foundation toward the sump, but if it's a high water table condition that's causing it you may have to demo the entire slab, dig down and backfill with clean 1/2-3/4" screenings (no fines) to get there.

Putting carpet of ANY kind in a basement with a flooding history is just BAD IDEA anywhere. Power failures are often related to storms an high bulk-water influx conditions. It WILL flood again, it's only a matter of when. Even if you had a dry basement, in Tarrytown the deep subsoil temps run about 50F, and the summertime outdoor air dew points average in the mid-60s. If you put an insulating air-permeable finish material like carpet on a slab, the slab will cool off, and the relative humidity deep in the carpet will soar, creating mold conditions. In your location it's advisable to put at least R4 of rigid foam (R8 is better) between the rug & soil to have any hope of keeping it from getting moldy. In new construction it's better to put it under the slab- 1.5" of XPS or 2" of EPS (the better choice, since it will retain all of it's R-value over the decades, whereas XPS loses ~10% over 50 years.). Without slab insulation, even if you took the room-air dew point down to 50F (the deep subsoil temp), there would still be a high RH at the bottom of a slab-mounted rug.

A 68F room temp w/ 50F dew point corresponds to 43% RH. Play around with an online psychrometric calculator a bit, and you'll see the problem- if you put an R1 rug down, the bottom half is going to be pretty cool, unless you have a much greater R value under it.

Short of demoing the whole slab and starting over, clean it up then use multiple applications of an appropriate concrete sealer can reduce the capillary draw through the slab, but if you want to finish the floor without insulating it, use only water/flood-tolerant materials, with a non-wicking vapor barrier type of underlayment, or you'll be re-doing it in a few years. See this. Unless you take the really serious approach to guaranteeing it won't flood again, you can't get away with the wooden subfloor over foam under a finished floor.

This is exactly why I'll never finish the basement fully in my place, but I've insulated the walls with rigid foam, air sealed it, etc. and I'll probably use a stain finish to the concrete if I want it to look nicer, but after better than a week without power after the ice storm of December 2008 there was 4" of water in the basement. About 3 days after hurricane Irene danced up the Hudson Valley in August 2011 my local water table temporarily rose to above the slab, even though I'm more than 100 miles east of the peak rainfall areas, and even WITH 4 sump pumps there was water flowing out of cracks in the middle of the floor over to the sumps. Your place doesn't look a whole lot better off (and possible worse off) than mine, in those regards.

I'm able to keep my basement under 60% RH all summer for about 400 kwh of power use per year with a standalone 70 pint room dehumidifier, after sealing and insulating the walls, and sealing the slab. The dehumidifier is set up with a drain hose, dripping directly into one of the sumps (through a tight-fitting sump cover.) With the concrete sealed, the basement RH tracks with summertime outdoor dew point averages- I only had to start running the dehumidifier on a couple of weeks ago during the 90F heat, but it'll probably duty-cycle all summer long until late September or early October, depending on weather cycles. At about 65% RH I can smell the difference in some corners of the basement, and my kid's asthma becomes an issue, so I hold the line at 60% (measured with a humidity monitor on the other end of the basement from the dehumidifier, which I tweak to suit.) A 30-pinter would keep up, but they're dramatically less efficient than the bigger units, but there's little incentive to go much bigger than an Energy Star 70.

For loss of power I have a generator that I will connect the circuit for the outlet for the sump pump via the transfer switch. That should take care of that. Of course, that entails that I am home to be able to crank up the generator so I'll take that chance.

I plan on using carpet tiles. These are the FLOR tiles and are connected to each other via small stickers - there is no glue at all and nothing actually binds to the concrete itself. It just sits on it.

I was considering maybe this product as it would seem to suit my needs -

I have a 7' ceiling so raising it up 1 3/8" with R8 I would like to avoid. The superseal product is 1/8" high.

I only have a few tiny spots where I see water coming *through* the floor - and these were due to someone nailing studs into the concrete for the finished side (that I gutted) for the framing. I think I can address with this some concrete epoxy patch such as the PC products one here:

Otherwise I have never seen water come up through the concrete other than that water main cutout in the original post pic.

Here are some pics of the dampness I see in the raw cinderblock wall as well as the floor.

In the last pic you can see I had some carbon fiber reinforcements put in. The south side foundation wall is buckled about 1/2" from plumb. When they prepped the wall for the carbon fiber they saw dampness as you can see in the pic. This is due to a leaking front stoop that I will address as well.

I will do as you say and fill in the sump with pea gravel and construct a cover for that as well as the water main cutout. I can use the home depot lid and cut out a hole for the pipe.

Thanks for the building science read. That was very informative as well.

First, you can fill in the space around the sump can with pea-gravel, and patch the slab with concrete at that location. You may want to cut in a fiber-cement board cover for the pit where the water main comes in, but leave it otherwise open.

Digging the sump deeper won't really address the water table or drainage issue much. As long as the water level is below the slab, being 2" below isn't much different from being 12" below. To get serious about it would require digging down to the footings along the entire perimeter and installing drain-tile pea gravel to direct the water incursions at the foundation toward the sump, but if it's a high water table condition that's causing it you may have to demo the entire slab, dig down and backfill with clean 1/2-3/4" screenings (no fines) to get there.

Putting carpet of ANY kind in a basement with a flooding history is just BAD IDEA anywhere. Power failures are often related to storms an high bulk-water influx conditions. It WILL flood again, it's only a matter of when. Even if you had a dry basement, in Tarrytown the deep subsoil temps run about 50F, and the summertime outdoor air dew points average in the mid-60s. If you put an insulating air-permeable finish material like carpet on a slab, the slab will cool off, and the relative humidity deep in the carpet will soar, creating mold conditions. In your location it's advisable to put at least R4 of rigid foam (R8 is better) between the rug & soil to have any hope of keeping it from getting moldy. In new construction it's better to put it under the slab- 1.5" of XPS or 2" of EPS (the better choice, since it will retain all of it's R-value over the decades, whereas XPS loses ~10% over 50 years.). Without slab insulation, even if you took the room-air dew point down to 50F (the deep subsoil temp), there would still be a high RH at the bottom of a slab-mounted rug.

A 68F room temp w/ 50F dew point corresponds to 43% RH. Play around with an online psychrometric calculator a bit, and you'll see the problem- if you put an R1 rug down, the bottom half is going to be pretty cool, unless you have a much greater R value under it.

Short of demoing the whole slab and starting over, clean it up then use multiple applications of an appropriate concrete sealer can reduce the capillary draw through the slab, but if you want to finish the floor without insulating it, use only water/flood-tolerant materials, with a non-wicking vapor barrier type of underlayment, or you'll be re-doing it in a few years. See this. Unless you take the really serious approach to guaranteeing it won't flood again, you can't get away with the wooden subfloor over foam under a finished floor.

This is exactly why I'll never finish the basement fully in my place, but I've insulated the walls with rigid foam, air sealed it, etc. and I'll probably use a stain finish to the concrete if I want it to look nicer, but after better than a week without power after the ice storm of December 2008 there was 4" of water in the basement. About 3 days after hurricane Irene danced up the Hudson Valley in August 2011 my local water table temporarily rose to above the slab, even though I'm more than 100 miles east of the peak rainfall areas, and even WITH 4 sump pumps there was water flowing out of cracks in the middle of the floor over to the sumps. Your place doesn't look a whole lot better off (and possible worse off) than mine, in those regards.

I'm able to keep my basement under 60% RH all summer for about 400 kwh of power use per year with a standalone 70 pint room dehumidifier, after sealing and insulating the walls, and sealing the slab. The dehumidifier is set up with a drain hose, dripping directly into one of the sumps (through a tight-fitting sump cover.) With the concrete sealed, the basement RH tracks with summertime outdoor dew point averages- I only had to start running the dehumidifier on a couple of weeks ago during the 90F heat, but it'll probably duty-cycle all summer long until late September or early October, depending on weather cycles. At about 65% RH I can smell the difference in some corners of the basement, and my kid's asthma becomes an issue, so I hold the line at 60% (measured with a humidity monitor on the other end of the basement from the dehumidifier, which I tweak to suit.) A 30-pinter would keep up, but they're dramatically less efficient than the bigger units, but there's little incentive to go much bigger than an Energy Star 70.

No matter how well you waterproof the slab, your subsoil temps are too low to get away with any type of carpet without at least some real R-value between the carpet & slab- there's no way to really cheat the physics. Carpets are insulating, and at the ~50F Tarrytown subsoil temp the relative humidity deep in the carpet will be high enough to support mold unless you mechanically lower the relative humidity of the room air to ~25-30% (well under a 40F dew point), the lower-limit of what's even healthy & comfortable for humans. Dehumidifying to that level also uses a lot of electricity, since that's at the lower-temp dew point end of what's achievable with standard dehumidifers (since the coil can't run too close to the freezing point without icing up.)

Hopefully you've dealt with the exterior grading and drainage issues to move bulk water away from the foundation(?), since that's a primary source of basement moisture. Even if you never finish the basement it's well worth air-sealing and insulating the foundtion walls including the foundation sill & band-joist. Fixing the moisture issues has to happen first though, and you can't just slap up a studwall with batts or you'll create a mold nightmare, even after the bulk water issues are addressed. A couple inches of rigid EPS faom against the foundation wall, seams & edges mastic or can-foam sealed, trapped in place with a studwall with UNFACED rock wool or fiberglass batts works. An inch or two of foam underneath the bottom plate of the studwall is needed too, as a capillary & thermal break from the cold-damp slab.There are other options too, which I can elaborate on if you're going there. In otherwise reasonably insulated homes, the heat losses through uninsulated foundations (even if not directly heated) often exceed 20% of the total heat load, sometimes more than 30%. Insulating & air sealing the foundation & band joist took close to 20% off my heating fuel use, but I've seen other homes where it was quite a bit more, and it raised the average mid-winter temp of my basement by more than 5F, lowering the the average RH.

In most basements the concrete floor is poured right up to the water and drain lines. I would not hesitate for a second to wrap the pipe with a sleeve and pour and finish the concrete where it is missing.

In most basements the concrete floor is poured right up to the water and drain lines. I would not hesitate for a second to wrap the pipe with a sleeve and pour and finish the concrete where it is missing.

Click to expand...

If you take look at the picture, there's a trap cleanout on the main drain in the same sump where the water service enters. Pouring concrete over that would guarantee that you'd need access to it in less than 2 years, according to the second corollary to Murphy's Law.

If you take look at the picture, there's a trap cleanout on the main drain in the same sump where the water service enters. Pouring concrete over that would guarantee that you'd need access to it in less than 2 years, according to the second corollary to Murphy's Law.

Click to expand...

That's what I thought! Although to be honest I've never cleaned it out in the 7 years I've been here. Do I expect to find the-most-digusting-things-I've-ever-seen when I open that trap up??

The only time I've had to open up mine was after my then 2-year old made a game of flushing some laundry down the toilet, only discovered after sewage from flushing backed up at the actual laundry area basin, overfilling and spilling onto the basement floor. You can bet I was happy to not be hammer-drilling through a slab in a couple inches of raw sewage to gain access to the trap, eh? (Yeah, it was pretty disgusting- the stinky shredded clothing plugging the trap being the least of it.)

Ha. Well I filled the sump pump with some bluestone gravel I had from when I had my driveway paved with asphalt. It's about the same size as pea gravel so why not use it. Filled it about 1" from the top or so and then covered with concrete mix from HD.

It took almost 4 full buckets of gravel to fill it up #(&*@#$(*&@$.

I drilled a 2" hole for the 1.5" ID PVC (pipe measures 1 7/8" OD) and then drilled a little side hole for the electrical cord.

Now I can still lift the cover if I need to actuate it manually. Knock on wood this thing works for a while.

Also covered up the water main area with some 1" rigid foam and some 2x4s for some weight. Not a perfect seal but I have the dang water pipe and the grounding wire to deal with. Any suggestions on how to fill the small gap in the rear (can't really see in the pic though)? This whole corner of the basement kind of stinks sometimes. I hope that doesn't mean I have some kind of sewer pipe issue.

With the 2x4s the foam sits pretty tight to the concrete. I might even consider caulking the edge since that will still enable me to yank it up if necessary. What do you think?

Only comment I have is I'd have put in a larger sump pit before making it all pretty. Most sump pump failures are due to the switch failing. With that small of a pit I can't imagine the pump runs for than 10sec before it's empty. How often does your pump run?